(6)To ensure the high quality of mixes of raw hops and hop products, in case of blends each of the consignments of hop cones used should meet the minimum quality requirements. In the case of blends of hop cones to be used as such, to maintain the special character conferred to the product by the variety and the production area, only hop cones of the same area and variety should be used. For hop products, a blend of hops of different varieties and/or production areas can be required to obtain a certain flavour profile, which is why such blends should be permitted and each variety and/or origin should be entered in the certificate, with indication of the percentage weight of each variety and/or production area, to allow traceability. Given that over time hops lose some of the alpha acid which influences their special flavour, only raw hops of the same harvest year should be blended, both for hop blends to be used as such and for hop products. In order to ensure that no elements which do not meet the requirements can be added, blended products of the hops sector should only be certified if they were blended under official surveillance in certification centres.